jdk/src/share/classes/java/lang/Throwable.java
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*** 1,7 ****
/*
! * Copyright (c) 1994, 2006, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
--- 1,7 ----
/*
! * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
*** 167,176 ****
--- 167,201 ----
*
* @serial
*/
private String detailMessage;
+ /*
+ * To allow Throwable objects to be made immutable and safely
+ * reused by the JVM, such as OutOfMemoryErrors, the three fields
+ * of Throwable that are writable in response to user actions,
+ * cause, stackTrace, and suppressedExceptions obey the following
+ * protocol:
+ *
+ * 1) The fields and initialized to a non-null sentinel value
+ *
+ * 2) Writing a null to the field indicates further writes
+ * are forbidden
+ *
+ * 3) The sentinel value may be replaced with another non-null
+ * value.
+ *
+ * For example, implementations of the HotSpot JVM have
+ * preallocated OutOfMemoryError objects to provide for better
+ * diagnosability of that situation. These objects are created
+ * without calling the constructor for that class and the fields
+ * in question are initialized to null. To support this
+ * capability, any new fields added to Throwable that require
+ * being initialized to a non-null value require a coordinated JVM
+ * change.
+ */
+
/**
* The throwable that caused this throwable to get thrown, or null if this
* throwable was not caused by another throwable, or if the causative
* throwable is unknown. If this field is equal to this throwable itself,
* it indicates that the cause of this throwable has not yet been
*** 187,221 ****
* @serial
* @since 1.4
*/
private StackTraceElement[] stackTrace;
/*
! * This field is lazily initialized on first use or serialization and
! * nulled out when fillInStackTrace is called.
*/
/**
* The list of suppressed exceptions, as returned by
! * {@link #getSuppressedExceptions()}.
*
* @serial
* @since 1.7
*/
! private List<Throwable> suppressedExceptions = null;
! /*
! * This field is lazily initialized when the first suppressed
! * exception is added.
! *
! * OutOfMemoryError is preallocated in the VM for better OOM
! * diagnosability during VM initialization. Constructor can't
! * be not invoked. If a new field to be added in the future must
! * be initialized to non-null, it requires a synchronized VM change.
! */
/** Message for trying to suppress a null exception. */
private static final String NULL_CAUSE_MESSAGE = "Cannot suppress a null exception.";
/** Caption for labeling causative exception stack traces */
private static final String CAUSE_CAPTION = "Caused by: ";
/** Caption for labeling suppressed exception stack traces */
private static final String SUPPRESSED_CAPTION = "Suppressed: ";
--- 212,245 ----
* @serial
* @since 1.4
*/
private StackTraceElement[] stackTrace;
/*
! * This field above is lazily initialized on first use or
! * serialization and nulled out when fillInStackTrace is called.
*/
+ // Setting this static field introduces an acceptable
+ // initialization dependency on a few java.util classes.
+ private static final List<Throwable> suppressedSentinel =
+ Collections.unmodifiableList(new ArrayList<Throwable>(0));
+
/**
* The list of suppressed exceptions, as returned by
! * {@link #getSuppressed()}.
*
* @serial
* @since 1.7
*/
! private List<Throwable> suppressedExceptions = suppressedSentinel;
/** Message for trying to suppress a null exception. */
private static final String NULL_CAUSE_MESSAGE = "Cannot suppress a null exception.";
+ /** Message for trying to suppress oneself. */
+ private static final String SELF_SUPPRESSION_MESSAGE = "Self-suppression not permitted";
+
/** Caption for labeling causative exception stack traces */
private static final String CAUSE_CAPTION = "Caused by: ";
/** Caption for labeling suppressed exception stack traces */
private static final String SUPPRESSED_CAPTION = "Suppressed: ";
*** 570,580 ****
StackTraceElement[] trace = getOurStackTrace();
for (StackTraceElement traceElement : trace)
s.println("\tat " + traceElement);
// Print suppressed exceptions, if any
! for (Throwable se : getSuppressedExceptions())
se.printEnclosedStackTrace(s, trace, SUPPRESSED_CAPTION, "\t", dejaVu);
// Print cause, if any
Throwable ourCause = getCause();
if (ourCause != null)
--- 594,604 ----
StackTraceElement[] trace = getOurStackTrace();
for (StackTraceElement traceElement : trace)
s.println("\tat " + traceElement);
// Print suppressed exceptions, if any
! for (Throwable se : getSuppressed())
se.printEnclosedStackTrace(s, trace, SUPPRESSED_CAPTION, "\t", dejaVu);
// Print cause, if any
Throwable ourCause = getCause();
if (ourCause != null)
*** 611,621 ****
s.println(prefix + "\tat " + trace[i]);
if (framesInCommon != 0)
s.println(prefix + "\t... " + framesInCommon + " more");
// Print suppressed exceptions, if any
! for (Throwable se : getSuppressedExceptions())
se.printEnclosedStackTrace(s, trace, SUPPRESSED_CAPTION,
prefix +"\t", dejaVu);
// Print cause, if any
Throwable ourCause = getCause();
--- 635,645 ----
s.println(prefix + "\tat " + trace[i]);
if (framesInCommon != 0)
s.println(prefix + "\t... " + framesInCommon + " more");
// Print suppressed exceptions, if any
! for (Throwable se : getSuppressed())
se.printEnclosedStackTrace(s, trace, SUPPRESSED_CAPTION,
prefix +"\t", dejaVu);
// Print cause, if any
Throwable ourCause = getCause();
*** 784,801 ****
throws IOException, ClassNotFoundException {
s.defaultReadObject(); // read in all fields
List<Throwable> suppressed = null;
if (suppressedExceptions != null &&
!suppressedExceptions.isEmpty()) { // Copy Throwables to new list
! suppressed = new ArrayList<Throwable>();
for (Throwable t : suppressedExceptions) {
if (t == null)
throw new NullPointerException(NULL_CAUSE_MESSAGE);
suppressed.add(t);
}
}
suppressedExceptions = suppressed;
}
private synchronized void writeObject(ObjectOutputStream s)
throws IOException
{
--- 808,839 ----
throws IOException, ClassNotFoundException {
s.defaultReadObject(); // read in all fields
List<Throwable> suppressed = null;
if (suppressedExceptions != null &&
!suppressedExceptions.isEmpty()) { // Copy Throwables to new list
! suppressed = new ArrayList<Throwable>(1);
for (Throwable t : suppressedExceptions) {
+ // Enforce constraints on suppressed exceptions in
+ // case of corrupt or malicious stream.
if (t == null)
throw new NullPointerException(NULL_CAUSE_MESSAGE);
+ if (t == this)
+ throw new IllegalArgumentException(SELF_SUPPRESSION_MESSAGE);
suppressed.add(t);
}
}
+
+ // If suppressed is a zero-length list, use the sentinel
+ // value.
+ if (suppressed != null && suppressed.isEmpty())
+ suppressedExceptions = suppressedSentinel;
+ else
suppressedExceptions = suppressed;
+
+ // Note that there are no constraints on the value the cause
+ // field can hold; both null and this are valid values for the
+ // field.
}
private synchronized void writeObject(ObjectOutputStream s)
throws IOException
{
*** 806,815 ****
--- 844,861 ----
/**
* Adds the specified exception to the list of exceptions that
* were suppressed, typically by the {@code try}-with-resources
* statement, in order to deliver this exception.
*
+ * If the first exception to be suppressed is {@code null}, that
+ * indicates suppressed exception information will <em>not</em> be
+ * recorded for this exception. Subsequent calls to this method
+ * will not record any suppressed exceptions. Otherwise,
+ * attempting to suppress {@code null} after an exception has
+ * already been successfully suppressed results in a {@code
+ * NullPointerException}.
+ *
* <p>Note that when one exception {@linkplain
* #initCause(Throwable) causes} another exception, the first
* exception is usually caught and then the second exception is
* thrown in response. In contrast, when one exception suppresses
* another, two exceptions are thrown in sibling code blocks, such
*** 817,855 ****
* control flow can only continue with one exception so the second
* is recorded as a suppressed exception of the first.
*
* @param exception the exception to be added to the list of
* suppressed exceptions
- * @throws NullPointerException if {@code exception} is null
* @throws IllegalArgumentException if {@code exception} is this
* throwable; a throwable cannot suppress itself.
* @since 1.7
*/
! public synchronized void addSuppressedException(Throwable exception) {
! if (exception == null)
! throw new NullPointerException(NULL_CAUSE_MESSAGE);
if (exception == this)
! throw new IllegalArgumentException("Self-suppression not permitted");
- if (suppressedExceptions == null)
- suppressedExceptions = new ArrayList<Throwable>();
suppressedExceptions.add(exception);
}
private static final Throwable[] EMPTY_THROWABLE_ARRAY = new Throwable[0];
/**
* Returns an array containing all of the exceptions that were
* suppressed, typically by the {@code try}-with-resources
* statement, in order to deliver this exception.
*
* @return an array containing all of the exceptions that were
* suppressed to deliver this exception.
* @since 1.7
*/
! public synchronized Throwable[] getSuppressedExceptions() {
! if (suppressedExceptions == null)
return EMPTY_THROWABLE_ARRAY;
else
return suppressedExceptions.toArray(EMPTY_THROWABLE_ARRAY);
}
}
--- 863,919 ----
* control flow can only continue with one exception so the second
* is recorded as a suppressed exception of the first.
*
* @param exception the exception to be added to the list of
* suppressed exceptions
* @throws IllegalArgumentException if {@code exception} is this
* throwable; a throwable cannot suppress itself.
+ * @throws NullPointerException if {@code exception} is null and
+ * an exception has already been suppressed by this exception
* @since 1.7
*/
! public synchronized void addSuppressed(Throwable exception) {
if (exception == this)
! throw new IllegalArgumentException(SELF_SUPPRESSION_MESSAGE);
!
! if (exception == null) {
! if (suppressedExceptions == suppressedSentinel) {
! suppressedExceptions = null; // No suppression information recorded
! return;
! } else
! throw new NullPointerException(NULL_CAUSE_MESSAGE);
! } else {
! assert exception != null && exception != this;
!
! if (suppressedExceptions == null) // Suppressed exceptions not recorded
! return;
!
! if (suppressedExceptions == suppressedSentinel)
! suppressedExceptions = new ArrayList<Throwable>(1);
!
! assert suppressedExceptions != suppressedSentinel;
suppressedExceptions.add(exception);
}
+ }
private static final Throwable[] EMPTY_THROWABLE_ARRAY = new Throwable[0];
/**
* Returns an array containing all of the exceptions that were
* suppressed, typically by the {@code try}-with-resources
* statement, in order to deliver this exception.
*
+ * If no exceptions were suppressed, an empty array is returned.
+ *
* @return an array containing all of the exceptions that were
* suppressed to deliver this exception.
* @since 1.7
*/
! public synchronized Throwable[] getSuppressed() {
! if (suppressedExceptions == suppressedSentinel ||
! suppressedExceptions == null)
return EMPTY_THROWABLE_ARRAY;
else
return suppressedExceptions.toArray(EMPTY_THROWABLE_ARRAY);
}
}